This proposal seeks support for the analysis of the first national longitudinal study of daily stressors and well-being. Biomarkers and self-reports of stress are combined to study individual and group differences in change in well-being during adulthood. Specific aims are: 1) To describe change over 10 years in links between multiple aspects of daily stressors (e.g., frequency, content, severity, appraised threat) and daily well-being;2) To examine how personal characteristics, including sociodemographic factors and personality, predict change in exposure to daily stressors and in physical and emotional reactivity to these stressors;and 3) To investigate how concurrent and cumulative exposure to daily stressors disrupt diurnal rhythms of salivary cortisol and lead to downstream health outcomes. These aims will be addressed by analyzing the second wave of the National Study of Daily Experiences (NSDE) approximately 10 years after wave one. NSDE I was an 8-day telephone diary study of 1483 adults ranging in age from 25-74 years of a U.S. national sample comprised of 10,389 daily interviews conducted in 1996. NSDE II repeats the 8-day protocol with the addition of multiple assessments of daily cortisol (4 occasions X 4 days) on the same respondents as well as a supplemental sample of African Americans. With 2,000 anticipated respondents, NSDE II will be the largest field study of diurnal salivary cortisol. NSDE respondents are a representative subsample of the two-wave Midlife in the United States (MIDUS) survey. A rich set of prospective and concurrent sociodemographic, physical health, and personality measures assessed by the MIDUS I and II surveys will be used to predict change in exposure and physical and emotional reactivity to daily stressors in NSDE I and II. Data from the MIDUS II biological project will be linked with NSDE I and II daily data to examine how patterns of exposure and reactivity to daily stressors correlate with measures of immune markers, endocrine functioning, and cardiovascular health. The combination of multiple daily stressors, personal characteristics, and biological measures permits a unique opportunity to show how characteristics of individuals and experiences in their daily lives create pathways to health and well-being.